Packaging

ABSTRACT

The invention relates to a package of a plastics material and consisting of a container and a lid adapted to be engaged with each other by snap engagement, there being provided complementary engagement faces which engage each other for establishing said snap engagement. An annular resilient sealing member is arranged between the engagement portion ( 40 ) and the bottom wall ( 19 ). The invention is characterized in that an axial compression of the sealing member ( 23 ) is provided during application of the lid ( 10 ), said compression being partially relieved when said engagement faces ( 29, 42 ) engage each other.

The invention relates to a plastics package of the type stated in theintroductory portion of claim 1, wherein a snap engagement is providedduring the application of a lid to a container. Such a package is knowne.g. from U.S. Pat. No. 5,143,219.

There is a need for providing a low-cost package that is suitable forthe transport of e.g. inflammable liquids. In particular, there is aneed for such a package as can meet the strict demands made by the UNwith respect to density, both at an internal positive pressure of 1 barliquid pressure and 0.4 bar gas pressure as well as after a drop testwhere the lid of the package is affected by a concentrated externalimpact. Even though for years numerous attempts have been made atproviding such packages of plastics (see e.g. U.S. Pat. No. 5,163,576),so far it has nevertheless been necessary to resort to metallic packagesin practice to ensure reliable properties. It has thus been observedthat the radial expansion of the known plastics containers combined withthe tendency of the plastics layer to bulge upwards during relativelylow internal pressures has given rise to release of the snap engagement,so that the mentioned UN specifications cannot be met.

The invention has made it possible to provide a low-cost package whichcan be made of a plastics material in a simple manner, and which meetsthe mentioned specifications.

This is achieved as stated in claim 1, wherein, during the establishmentof a snap engagement between the lid and the container of the package,first a compression and then a partial relief of a sealing memberembedded between the lid and the container are provided. This greatlyobviates the situation that an internal pressure in the container and anexternal impact can cause the snap engagement to be released. Whenpreferably the lid and the container are formed with inclinedcooperating engagement faces, a particularly simple structure isachieved.

As stated in claim 5, the sealing member is preferably arranged in thelid, whereby damage to the sealing member during the application of thelid to the container is avoided to the greatest extent possible.

When the package is formed so as to provide a ring-shaped space, asstated in claim 6, a particularly effective sealing of the package isachieved.

The invention moreover relates to a lid for a container for providing apackage of the type stated initially. The invention also relates to anexpedient mould for the manufacture of the lid.

The invention will now be explained more fully with reference to theembodiment shown in the drawing. In the drawing:

FIG. 1 shows a portion of a package according to the invention, seen incross-section,

FIG. 2 shows the lid shown in FIG. 1 for the package,

FIG. 3 shows the container shown in FIG. 1 for the package, and

FIGS. 4a-4 d show the manufacture of the lid shown in FIG. 2 using amould according to the invention.

In FIG. 1, the reference numeral 1 generally designates a packageconsisting of a container 30 with an applied lid 10. The container 30and the lid 10 extend symmetrically around an axis of symmetry CL. Boththe container 30 and the lid 10 are made of a plastics material bymoulding.

As mentioned initially, there is a need for providing a low-cost packagewhich is suitable for the transport of inflammable liquids among otherthings. In particular, there is a need for such a package as can meetthe strict requirements made by the UN with respect to density, both atan internal positive pressure of 1 bar liquid pressure and 0.4 bar gaspressure as well as after a drop test. Even though for years numerousattempts have been made at providing such packages of plastics, so farit has nevertheless been necessary to resort to metallic packages inpractice to ensure reliable properties.

The shown container 30 is formed by a cylindrical wall 32 which, at itslowermost end, is connected with a bottom (not shown) for the container.Opposite the bottom, the wall 32 has an annular free edge 35. Outermost,the lid 10 has a skirt 14 which forms a downwardly open receptionchannel. When the lid 10 is applied to the container 30, the free edge35 is moved into the reception channel until a position in which a snapengagement is established between the lid 10 and the container 30 bysnap action. The snap engagement causes an engagement face 29 on the lid10 to engage a complementary engagement face 42 on the container 30,which provides an effective fixing of the lid 10 on the container 30. Toallow subsequent emptying of the package 1, the lid 10 may be formedwith a separate opening.

As shown in FIG. 1, the package 1 also comprises an annular elasticsealing member 23. When the snap engagement has been established betweenthe lid 10 and the container 30, the sealing member 23 engages thebottom wall 19 of the reception channel of the lid 10 with a certainbias and engages an outwardly extending annular rib 31 on the outer sideof the wall 32. A ring-shaped space 5 is provided outermost between therib 31 and the skirt 14, said space having a radial extent whichdecreases in a direction away from the sealing member 23, as shown.

FIG. 2 shows the lid 10 alone. It will be seen that the lid 10 comprisesa face portion 12 connected with said skirt 14. As mentioned, the skirt14 forms the reception channel, which is indicated by the referencenumeral 15, of the lid, said skirt 14 comprising a first side wall 17, asecond side wall 25 and the bottom wall 19. The first side wall 17 isconnected with the face portion 12 via an annular wall 11, and thisconnection is stiffened by means of ribs 13 which are directed radiallyfrom the axis CL and are arranged at a mutual distance around the axisCL. The second side wall 25 has a free end with an end face 28 extendingobliquely in a direction up toward the face portion 12.

The lid 10 moreover has engagement means 27 arranged on the second sidewall 25 in the vicinity of the end face 28. As shown, the engagementmeans 27 consist of a plane annular engagement face 29 which extendsobliquely relative to the axis of symmetry CL at an angle α. The angle αis preferably between about 15° and about 40°, preferably about 30°relative to a normal to the axis CL. An inclined face 26 connects theengagement face 29 with the end face 28.

It will moreover be seen that an annular projection 21 is arranged onthe bottom wall 19. A groove-shaped depression is defined between theprojection 21 and the second side wall 25, as shown, said depressionforming a face 20 in which the sealing member 23 is embedded. Thesealing member 23 is preferably made of synthetic rubber.

FIG. 3 shows a portion of the container 30 according to the invention.Outermost on the wall 32, at a short distance below the free end 35,there is arranged an engagement portion which is generally designated bythe reference numeral 40, and which is formed to establish a tight andreliable snap engagement with the lid 10. The engagement portion 40comprises the above-mentioned rib 31 and an underlying annular rib 41.The two ribs 31, 41 are interconnected by radially directed ribs 44arranged at a mutual distance around the axis CL. The upper rib 31 hasan outer plane end edge 37 which preferably extends at an angle of about5° relative to the axis CL, and an upper projection 39 arranged on theface 38 which defines the upper side of the rib 31. This angle may e.g.be selected to be between about 3° and about 15°. The function of theprojection 39 will be explained more fully below.

As will be seen, the rib 41 is formed on the underside with a planeannular engagement face 42 which extends obliquely relative to the axisof symmetry CL at an angle α, i.e. in parallel with the engagement face29 on the lid 10. The engagement face 29 preferably has such a shape anddimension that it can engage the engagement face 42 over its entire areaonce the snap engagement has been established.

It will be appreciated that by application of the lid 10 to thecontainer 30 the second side wall 25 will be deformed elasticallyradially outwards, while the inclined face 26 is moved along the ribs31, 41 and 44. During this, compression of the sealing member 23 isprovided. When the second side wall 25 then bends back to the startingportion, at the moment when the inclined face 26 moves past the rib 41on the container 30, said snap engagement is established, while reliefof the sealing member takes place simultaneously because of the shape ofthe engagement faces 29, 42, when the lid subsequently moves slightlyupwards during the short movement of the engagement face 29 on theengagement face 42. In this position, the sealing member 23 engages boththe face 20 on the lid 10 and the face 38 on the rib 31, as shown inFIG. 1, and the projection 39 will moreover provide a localized annulardeformation of the sealing member 23. This deformation causes part ofthe sealing member 23 to be pressed into the ring space 5 between theend edge 37 of the rib 31. Since the ring space 5 is wedge-shaped,preferably because of the oblique extent of the end edge 37 relative tothe vertical axis CL, additional compression of the part of the materialof the sealing member 23 that is pressed into the ring space 5 isachieved, which results in an increase in the sealing properties of thepackage.

It will be appreciated that the cooperating annular engagement faces 29,42 are preferably plane; however, nothing prevents the engagement facesfrom bulging up-wards.

FIG. 4a shows a portion of a mould for use in the manufacture of the lidfor the package described above. The mould comprises a female mould part100, a male mould part 110 and an ejector ring 120 that surrounds themale mould part 110. These mould parts together define a mould cavityfor the lid 10 into which a plastics moulding material is injected bymeans of devices not shown. The ejector ring 120 has a surface portion122 which forms a moulding face for the inclined end face 28 of the lidduring moulding. The male mould part 110 moreover has a recess 112 forproviding the engagement face 29 of the lid 10.

FIGS. 4b-4 d show how the moulded lid is pressed out of the male mouldpart 110. The female mould part 100 is first removed as shown in FIG.4b, following which the ejector ring 120 is moved vertically upwards inthe direction of the arrow P as shown in FIG. 4c, so that the surfaceportion 122 moves along the inclined end face 28. This upwardly directedmovement of the ejector ring 120 gives rise to an outwardly directedforce on the finished lid 10, causing the second end wall 25 of theskirt to yield outwards, so that the engagement face 29 clears therecess 112, and so that the lid may then be pressed out of the malemould part 110 by a continued upward movement of the ejector ring 120.

EXAMPLE

A package of the type described above with reference to the drawing wasmanufactured. The container had a diameter of 30 cm and a height fromthe bottom to the free edge 35 of 40 cm. The wall thickness of thecontainer was 0.2 cm and the thickness of the lid was 0.2 cm. Thepackage was made of HDPE, and a sealing member made of DUROTAK H2036Emanufactured by National Starch & Chemical AB, of Sweden, was selected.The ribs 31 and 41 had a thickness of 0.1 and 0.2 cm, respectively, andthe angle α of the face 29 and 42 was selected to be 22°.

By application of an inner positive air pressure of 0.4 bar and aninternal liquid pressure of 1 bar a sufficient density was observed tomeet UN standard No. 1H2/Y/100/-. The package was likewise able towithstand the drop test described in the same standard.

What is claimed is:
 1. A package of a plastics material and consistingof a container and a lid, said container having a bottom connected witha cylindrical wall extending around an axis (CL), said wall, oppositethe bottom, having a free end which defines an opening that gives accessto the interior of the container, said wall having an annular engagementportion on the outer side at its free end, said lid comprising asubstantially disc-shaped face portion with a peripheral skirt whichforms an annular reception channel, extending around said axis (CL), forsaid free end, said reception channel being defined by a first sidewall, a second side wall and a bottom wall, said first side wall beingconnected with the disc-shaped face portion, said second side wallcomprising engagement means adapted to form a snap engagement with theengagement portion, said engagement portion and said engagement meanscomprising complementary engagement faces adapted to engage each otherfor establishing said snap engagement, said engagement faces beingmutually parallel and planar and extending obliquely at an angle α ofbetween about 15° and about 40° relative to a normal to the axis CL,there being arranged between the engagement portion and the bottom wallan annular resilient sealing member which extends around the entirereception channel, and which, once said snap engagement has beenestablished, engages an annular first face arranged in the receptionchannel and a second annular face arranged on the container at said freeend, wherein said first face or second face exhibits an annularprojection adapted to generate a further, local compression of thesealing member when the engagement faces engage each other, wherein saidfirst face arranged in the reception channel defines an annular groove,and said sealing member is secured in the groove by adhesion or inanother manner, and said second face exhibits the annular projectionadapted to generate said additional, local compression of the sealingmember, wherein the engagement portion and the engagement means areshaped such that an axial compression of the sealing member is providedduring the application of the lid, said compression being partiallyrelieved when said engagement faces engage each other, wherein radiallyoutwards from the axis (CL) and in extension of said annular projection,the engagement portion exhibits an end edge arranged opposite the secondside wall of the reception channel, and wherein the end edge and saidsecond side wall between them define a ring-shaped space whose radialextent decreases in a direction away from the sealing member.
 2. Apackage according to claim 1, wherein the sealing member is secured tosaid first face by adhesion.
 3. A package of plastics material andconsisting of a container and a lid, said container having a bottomconnected with a cylindrical wall extending around an axis (CL), saidwall, opposite the bottom, having a free end which defines an openingthat gives access to the interior of the container, said wall having anannular engagement portion on the outer side at its free end, said lidcomprising a substantially disc-shaped face portion with a peripheralskirt which forms an annular reception channel extending around saidaxis (CL), for said free end, said reception channel being defined by afirst side wall, a second side wall and a bottom wall, said first sidewall being connected with the disc-shaped face portion, said second sidewall comprising engagement means adapted to form a snap engagement withthe engagement portion, said engagement portion and said engagementmeans comprising complementary engagement faces adapted to engage eachother for establishing said snap engagement, there being arrangedbetween the engagement portion and the bottom wall an annular resilientsealing member which extends around the entire reception channel, andwhich, once said snap engagement has been established, engages anannular first face arranged in the reception channel and a secondannular face arranged on the container at said free end, wherein theengagement portion and the engagement means are shaped such that anaxial compression of the sealing member is provided during theapplication of the lid, said compression being partially relieved whensaid engagement faces engage each other, wherein radially outwards fromthe axis (CL) and in extension of said annular projection, theengagement portion exhibits an end edge arranged opposite the secondside wall of the reception channel, and wherein the end edge and saidsecond side wall between them define a ring-shaped space whose radialextend decreases in a direction away from the sealing member.
 4. A mouldfor the manufacture of a lid comprising a substantially disc-shaped faceportion with a peripheral skirt which forms an annular reception channelextending around said axis (CL) for the free end of a container, saidreception channel being defined by a first side wall, a second side walland a bottom wall, said first side wall being connected with thedisc-shaped face portion, said second side wall comprising engagementmeans adapted to form a snap engagement with an engagement portion onsaid container, said engagement means comprising an engagement facewhich extends obliquely relative to said axis (CL) at an angle α ofbetween about 20° and about 40° relative to a normal to the axis CL, anannular sealing means being secured in the reception channel byadhesion, said free end of said second side wall comprising an inclinedend face which extends approximately in parallel with said engagementface on the lid, said lid being manufactured using a female mould part,a male mould part and an ejector ring, which together define a mouldcavity for the lid, said ejector ring being adapted to be moved in adirection of said axis (CL) to release a lid just moulded from the malemould part, characterized in that the ejector ring defines a mouldingface for said inclined end face on the lid.